Heat Exchanger And Corresponding Flat Tube And Plate

ABSTRACT

A heat exchanger for cooling charge air comprises at least one flat tube for circulation of a fluid. The flat tube is formed by assembling a pair of plates ( 7 ) in such a way as to define a first circulation channel ( 23 ) and a second circulation channel ( 25 ). The circulation channels ( 23, 25 ) communicate with one another at one end to establish substantially “U”-shaped circulation path for the fluid. At least one plate ( 7 ) comprises at least one first rib ( 29 ) and one second rib ( 31 ). The first and second ribs ( 29, 31 ) are substantially “L”-shaped. The first rib ( 29 ) is arranged in the first circulation channel ( 23 ) and the second rib ( 31 ) is arranged in the second circulation channel ( 25 ). A flat tube and a plate for such a heat exchanger are also disclosed.

The invention relates to a heat exchanger notably for a motor vehicle.

A heat exchanger, for example used in the automotive industry and more specifically in a motor vehicle internal combustion engine, comprises elements for the exchange of heat and the flow of fluid through which elements fluids which exchange heat with one another circulate.

Numerous combinations of fluids can be imagined, whether these be liquids and/or gases. It is notably possible to conceive of what is referred to as an “air-water” exchanger, such as a charge air cooler.

The heat exchange elements may for example comprise flat tubes, fins that disrupt the circulation of gas and/or features that disrupt the flow of fluid or the like.

There are numerous conceivable structural configurations.

Exchangers comprising a core of plates which are arranged in mutually parallel pairs in one or more mutually parallel rows are known. The pairs of plates are arranged in such a way as to define firstly a flow passage for a first fluid and secondly a gap between two adjacent pairs of plates through which gap a second fluid can flow, exchanging heat with the first fluid.

In a known solution, each plate may define two or several circulation passes. Each pass is defined by a circulation canal.

By way of example, a plate for an exchanger flat tube is generally defined with four passes.

Plates defined with two passes are also known.

However, to ensure good mechanical integrity it is necessary to make the plate more dense. One known way of achieving that is to create a multitude of bosses, for example spots of braze material.

It is an objective of the invention to further improve the performance of known heat exchangers, in terms of reduction of mechanical stresses and losses in pressure head.

To this end, one subject of the invention is a heat exchanger for cooling charge air, said exchanger comprises at least one flat tube for the circulation of a fluid, formed by assembling a pair of plates, thereby delimiting a first circulation canal and a second circulation canal, which are such that said canals communicate with one another at one end to define a substantially U-shaped circulation path for said fluid, characterized in that at least one plate comprises at least one first rib and one second rib which are substantially L-shaped overall; and in that said at least one first rib and second rib is arranged in said first circulation canal and said second circulation canal, respectively.

Said exchanger may further comprise one or more of the following features, considered separately or in combination:

-   -   said at least one plate comprises a central rib, said central         rib projecting into said at least one flat tube to delimit the         first and second circulation canals;     -   said at least one first and second ribs are symmetric about said         central rib;     -   said at least one first rib extends substantially at the center         of the width of said first canal, and said at least one second         rib extends substantially at the center of the width of said         second canal;     -   said at least one plate comprises a fluid inlet orifice arranged         in said first circulation canal, and a fluid outlet orifice         arranged in said second circulation canal, and said at least one         first rib is substantially aligned with respect to the center of         said inlet orifice, and said at least one second rib is         substantially aligned with respect to the center of said outlet         orifice;     -   said substantially L-shaped ribs have rounded edges;     -   said at least one plate has a plurality of bosses that project         into the flow passage for said fluid;     -   said at least one plate has a width less than or equal to 100         mm.

The invention also relates to a flat tube for a heat exchanger as claimed in any one of the preceding claims, said tube being formed by assembling a pair of plates, thereby delimiting a first circulation canal and a second circulation canal, which are such that said canals communicate with one another at one end to define a substantially U-shaped circulation path for said fluid, characterized in that at least one plate comprises at least one first rib and one second rib which are substantially L-shaped overall; said at least one first rib and second rib is arranged in said first circulation canal and said second circulation canal, respectively.

Said tube may further have one or more of the following features, considered separately or in combination:

-   -   the two plates of said pair of plates are substantially         identical;     -   said plates respectively comprise a central rib and the central         rib of a first plate is in contact with the central rib         opposite, belonging to the second plate;     -   said first and second ribs of the first plate are respectively         in contact with said first and second ribs opposite, belonging         to the second plate.

The invention further relates to a plate for a flat tube of a heat exchanger delimiting a first circulation canal and a second circulation canal, said canals communicating with one another at one end to define a substantially U-shaped circulation path for said fluid, characterized in that said plate comprises at least one first rib and one second rib which are substantially L-shaped overall; said at least one first rib and second rib being arranged in said first circulation canal and said second circulation canal, respectively.

Further features and advantages of the invention will become more clearly apparent from reading the following description, given by way of nonlimiting illustrative example, and from studying the attached drawings in which:

FIG. 1 depicts a side view of a plate-type heat exchanger;

FIG. 2 depicts a plate of the exchanger of FIG. 1.

In these figures, elements that are substantially identical bear the same references.

The invention relates to a heat exchanger, particularly for cooling the charge air of a combustion engine, such as a motor vehicle engine.

Such an exchanger may be an exchanger of what is referred to as the “air-water” type, namely an exchanger in which the fluids that exchange heat are air and water. In the case of a charge air cooler, the water is preferably water from what is referred to as the “low temperature” cooling circuit of said engine; this is typically water containing glycol.

FIG. 1 depicts a heat exchanger 1 in side view.

The exchanger 1 has, for example, a substantially parallelepipedal overall shape.

The exchanger 1 comprises a stack of flat tubes 3.

The flat tubes 3 may be positioned to alternate with interleaved spacers 5.

An interleaved spacer 5 is, for example, formed from a thin corrugated thermally conductive sheet, the crests of which are in contact with the two flat tubes 3 alternately, on either side of the interleaved spacer 5.

A flow of air may circulate through the interleaved spacers 5, to exchange heat with the fluid circulating in the flat tubes 3. The interleaved spacers 5 disturb the flow of air to increase the surface area for exchange.

According to the embodiment described, all the flat tubes 3 are identical.

Each tube is, for example, formed by assembling a pair of plates 7 facing each other. The exchanger 1 is therefore of the plate type.

The assembled plates 7 between them define a passage 9 for the flow of a fluid, particularly a coolant. Such a passage 9 may have a substantially constant thickness.

A plate 7 (best visible in FIG. 2) has a rectangular overall shape with a length L and a width 1.

By way of example, the plate 7 has a width 1 less than or equal to 100 mm.

Further, the plate 7 has for example a length L of between 120 mm and 280 mm.

Each plate 7 comprises orifices forming a fluid inlet 11 to introduce fluid into the fluid flow passage 9 and a fluid outlet 13 for removing the fluid.

A plate 7 additionally comprises, at the fluid inlet 11 and the fluid outlet 13 of the plates 7, bulges 15 (cf. FIG. 1). These bulges 15 are oriented toward the outside of the fluid flow passage 9.

The bulges 15 of one plate 7 communicate with the bulges 15 of a plate 7 of an adjacent pair of plates 7. Because of the bulges 15, the stacking of flat tubes 3 creates a gap between two adjacent pairs of plates 7. These gaps can be filled with an interleaved spacer 5 as described hereinabove.

Further, as may be seen in FIG. 1, the exchanger 1 respectively comprises two, inlet and outlet, nozzles 17, for the passage of a fluid. These nozzles 17 respectively communicate with the bulges 15 and associated orifices 11, 13 of the plates 7 to allow the fluid to circulate between the plates 7.

Moreover, according to the embodiment illustrated in FIGS. 1 and 2, the plates 7 are made from chased sheet.

Such chased plates 7 are substantially dish shaped.

Each plate 7 comprises a peripheral edge 19 forming a contour of the plate 7.

The plates 7 of one and the same pair are joined together in a fluid-tight fashion around their entire contour at their respective peripheral edge 19 to define a passage 9 for the flow of the fluid. The plates 7 are arranged in such a way that their concave regions face one another.

As an alternative, it is possible to plan to assemble such a chased plate 7 with a planar plate that rests on the peripheral contour 19 of the chased plate 7 in order to define the fluid flow passage 9.

The plates 7 are joined together in a fluid-tight fashion for example by brazing.

In addition, a chased plate 7 as illustrated in FIG. 2, defines two circulation passes.

For that purpose, the plate 7 comprises a central rib 21. This central rib 21 is positioned substantially at the center of the width 1 of a plate 7.

This central rib 21 is arranged on the interior surface of the plate, i.e. facing the fluid flow passage 9, so that the central rib 21 projects into the fluid flow passage 9.

The central rib 21 is a longitudinal rib joining two plates 7 of a pair so as to define two circulation passes for the fluid.

In the case of a flat tube 3 that is formed by assembling two chased plates 7, the central rib 21 of the first plate 7 is kept in contact with the central rib 21 facing it, belonging to the second plate 7.

According to an alternative form with a chased plate 7 assembled with a planar plate, the latter rests against the central rib 21 of the chased plate 7.

A partition is thus created in the fluid flow passage 9.

This partition delimits a first circulation canal 23 and a second circulation canal 25 thus forming two passes with a U-shaped circulation between the fluid inlet 11 and the fluid outlet 13. The first pass is defined by the first circulation canal 23 and the second pass is defined by the second circulation canal 25.

In addition, this central rib 21 may have a rounded end 27.

Such a plate 7 further comprises at least one first secondary rib 29 and at least one second secondary rib 31.

These two secondary ribs 29 and 31 serve to strengthen the plate 7 mechanically.

The first rib 29 is arranged in the first circulation canal 23 in such a way as to divide it into two sub-canals 23 a and 23 b.

Similarly, the second secondary rib 31 is arranged in the second fluid circulation canal 25 in such a way as to divide it into two sub-canals 25 a and 25 b.

Arranging secondary ribs 29 and 31 in the U-shaped circulation canals in this way makes it possible to channel the flow of fluid in the fluid flow passage 9.

Furthermore, the secondary ribs 29, 31 are substantially L-shaped overall. This L shape allows mechanical strength to be combined with reduction in pressure head losses. This is because by using substantially L-shaped secondary ribs, the applicant company has discovered a better compromise between mechanical stress and pressure head loss.

Moreover, the substantially L-shaped secondary ribs 29, 31 may have rounded edges so that they do not have any sharp corners, thus equalizing the fluid flow better.

In addition, these two ribs are therefore arranged one on either side of the central rib 21.

More specifically, the first secondary rib 29 and the second secondary rib 31 are symmetric about the central rib 21.

Furthermore, for more uniform distribution of flow, the secondary ribs 29 and 31 are respectively arranged substantially at the center, widthwise, of the associated circulation canal 23, 25. This is because the first rib 29 extends substantially at the center of the width of the first canal 23, and the second rib 31 extends substantially at the center of the width of the second canal 25.

Moreover, according to the embodiment illustrated, the first rib is substantially aligned with respect to the center of the inlet orifice 11.

Likewise, the second rib is substantially aligned with respect to the center of the outlet orifice 13.

Finally, the plate 7 may even have a multitude of bosses 33 on its interior surface. Thus, these bosses 33 project into the fluid flow passage 9.

The bosses 33 are, for example, spots of braze material.

Thus, such plates 7 with the substantially L-shaped secondary ribs 29, 31 substantially in the middle of each fluid circulation canal 23, 25 improve the mechanical strength of the plate 7 while at the same time equalizing the flow of the fluid.

This arrangement is particularly suited to plates 7 less than 100 mm in width.

This is because for such plates, the applicant company has found that using two-pass plates offers a better compromise than the use of multi-pass plates; each pass being formed by one circulation canal. Further, partitioning the two canals of the plate into two passes using L-shaped secondary ribs makes it possible further to improve the performance in terms of mechanical integrity and pressure head losses.

Furthermore, the applicant company has found that it is possible to reduce mechanical stresses by as much as 35% by using such plates 7 according to the invention, as compared with chased plates that define two passes but do not have the L-shaped secondary ribs substantially in the middle of the two passes.

This novel type of two-pass plate 7 subdivided by L-shaped ribs therefore allows the heat exchange performance of the exchanger 1 to be further improved. 

1. A heat exchanger for cooling charge air, said exchanger comprising at least one flat tube for the circulation of a fluid, said at least one flat tube being formed by assembling a pair of plates, thereby delimiting a first circulation canal and a second circulation canal, such that said circulation canals communicate with one another at one end to define a substantially U-shaped circulation path for the fluid, wherein at least one plate comprises at least one first rib and one second rib which are substantially L-shaped overall, and wherein said first rib is arranged in said first circulation canal and said second rib is arranged in said second circulation canal.
 2. The exchanger as claimed in claim 1, wherein said at least one plate comprises a central rib, with said central rib projecting into said at least one flat tube to delimit said first and second circulation canals.
 3. The exchanger as claimed in claim 2, wherein said at least one first and second ribs are symmetric about said central rib.
 4. The exchanger as claimed in claim 1, wherein said at least one first rib extends substantially at the center of the width of said first circulation canal, and in wherein said at least one second rib extends substantially at the center of the width of said second circulation canal.
 5. The exchanger as claimed in claim 1, wherein said at least one plate comprises a fluid inlet orifice arranged in said first circulation canal, and comprises a fluid outlet orifice arranged in said second circulation canal, and wherein said at least one first rib is substantially aligned with respect to the center of said inlet orifice, and said at least one second rib is substantially aligned with respect to the center of said outlet orifice.
 6. The exchanger as claimed in claim 1, wherein said substantially L-shaped ribs have rounded edges.
 7. The exchanger as claimed in claim 1, wherein said at least one plate has a plurality of bosses that project into a flow passage for the fluid.
 8. The exchanger as claimed in claim 1, wherein said at least one plate has a width less than or equal to 100 mm.
 9. A flat tube for a heat exchanger as claimed in claim 1, said flat tube being formed by assembling a pair of plates, thereby delimiting a first circulation canal and a second circulation canal, such that said circulation canals communicate with one another at one end to define a substantially U-shaped circulation path for the fluid, wherein at least one plate comprises at least one first rib and one second rib which are substantially L-shaped overall, and wherein said first rib is arranged in said first circulation canal and said second rib is arranged in said second circulation canal.
 10. The flat tube as claimed in claim 9, wherein the two plates of said pair of plates are substantially identical.
 11. The flat tube as claimed in claim 10, wherein each of said plates respectively comprise a central rib and wherein a central rib of a first plate is in contact with a central rib of a second plate.
 12. The flat tube as claimed in claim 10, wherein said first and second ribs of said first plate are respectively in contact with said first and second ribs of said second plate.
 13. A plate for a flat tube of a heat exchanger as claimed in claim 9, said plate delimiting a first circulation canal and a second circulation canal, said circulation canals communicating with one another at one end to define a substantially U-shaped circulation path for the fluid, wherein said plate comprises at least one first rib and one second rib which are substantially L-shaped overall, and wherein said first rib is arranged in said first circulation canal and said second rib is arranged in said second circulation canal.
 14. The exchanger as claimed in claim 2, wherein said at least one first rib extends substantially at the center of the width of said first circulation canal, and wherein said at least one second rib extends substantially at the center of the width of said second circulation canal.
 15. The exchanger as claimed in claim 3, wherein said at least one first rib extends substantially at the center of the width of said first circulation canal, and wherein said at least one second rib extends substantially at the center of the width of said second circulation canal.
 16. The exchanger as claimed in claim 2, wherein said at least one plate comprises a fluid inlet orifice arranged in said first circulation canal, and comprises a fluid outlet orifice arranged in said second circulation canal, and wherein said at least one first rib is substantially aligned with respect to the center of said inlet orifice, and said at least one second rib is substantially aligned with respect to the center of said outlet orifice.
 17. The exchanger as claimed in claim 3, wherein said at least one plate comprises a fluid inlet orifice arranged in said first circulation canal, and comprises a fluid outlet orifice arranged in said second circulation canal, and wherein said at least one first rib is substantially aligned with respect to the center of said inlet orifice, and said at least one second rib is substantially aligned with respect to the center of said outlet orifice.
 18. The exchanger as claimed in claim 4, wherein said at least one plate comprises a fluid inlet orifice arranged in said first circulation canal, and comprises a fluid outlet orifice arranged in said second circulation canal, and wherein said at least one first rib is substantially aligned with respect to the center of said inlet orifice, and said at least one second rib is substantially aligned with respect to the center of said outlet orifice. 